Polar cap observations of mesospheric and lower thermospheric 4‐hour waves in temperature

Abstract

Lower thermospheric and upper mesospheric rotational temperatures have been derived from ground‐based measurements of the O2(0–1) and OH(6–2) nightglow emissions over Resolute Bay, Canada (74.68°N, 94.90°W) and OH(4–2) nightglow emission over Kiruna, Sweden (67.90°N, 21.10°E). From measurements taken during two nights in November, 2001, we have observed a dominant and coherent 4‐hr oscillation in both the O2 and OH airglow emission rates and rotational temperatures. The phases for the two oscillation events remain almost constant at each location, indicating that these oscillations may not be caused by transient passage of instantaneous gravity waves. More importantly, there is little phase difference in universal time between the 4‐hr oscillations in temperature at Resolute and Kiruna. The small phase difference gives a strong indication that the oscillation maybe related to a zonally symmetric tide, since any tidal waves in temperature with a nonzero zonal wavenumber are very weak at high latitudes. Waves in both events have large vertical wavelengths (76 and 175 km). The 4‐hr wave shows almost no latitudinal variation from Resolute to Kiruna.

Airglow variability in the context of the global mesospheric circulation

“…It is an imager with narrow-band filters for the O 2 (0,1) atmospheric band and the OH (6,2) Meinel band in which radial distance on the image gives the spectrum and the tangential angle the azimuthal position on the sky. It is described in detail by Sargoytchev et al (2004) and high latitude results have been presented on a 4-h oscillation by Won et al (2003) and on mesospheric cooling by Cho et al (2004).…”

Tidal features in the wintertime mesospheric temperature and neutral winds recorded at Resolute Bay, Canada (74.68°N, 94.90°W)

“…concluded that the measured 6-h quasi-monochromatic variation of the winter mesopause represented the effect of an s ¼ 0 non-migrating tidal oscillation, though the source of the excitation remained in question. Won et al (2003) verified that the 4-h oscillation in the northern high-latitude mesosphere temperature was an s ¼ 0 non-migrating oscillation based on observations from multiple stations.…”

Comparison of OH rotational temperatures measured by the spectral airglow temperature imager (SATI) and by a tilting-filter photometer

“…It should be noted that the low OH temperature of SATI is signiÿcant not only for our SATI in Japan, but also for other SATIs in Spain (Là opez-Gonzà alez et al, 2003), Saskatchewan (Chshyolkova, 2003), and Resolute Bay (Won et al, 2003). Detailed analyses of SATI data from Resolute Bay also suggests the importance of the empirically-determined Q-branch coe cients (G.G.…”